Posted: 27th August 2019
Posted in: News
The term, “peripheral neuropathy” simply describes any nerve pathology within the peripheral nervous system.
These can be focal in nature (e.g., a carpal tunnel syndrome, which is specific to a median nerve entrapment at the carpal tunnel) or more generalised (e.g., widespread degeneration in the peripheral nervous system caused by diabetes).
Peripheral neuropathy affects a large portion of the population, encompassing a wide range of conditions, with a wide variety of causes and presenting symptoms (e.g., numbness, pain, burning or tingling sensations).
The main goal of any neurological investigation is to determine the location and type of pathology; this is particularly true in the case of a suspected peripheral neuropathy.
A difficulty that clinicians face in diagnosing a peripheral neuropathy or polyneuropathy often lies with the fact that related symptoms are often “invisible” and subjective (e.g. impaired cutaneous sensation – pain or temperature).
Furthermore, symptoms can often mimic other pathologies and it can become easy to “assume” a diagnosis without clear, objective evidence to the contrary.
A thorough examination and case history will not always provide clinicians with the necessary evidence to make an accurate diagnosis. Neurophysiology testing can sometimes assist in this regard.
The main diagnostic tools used to determine peripheral neuropathy are nerve conduction studies (NCS) and needle electromyography (EMG), which have the ability to localise conduction problems along the course of nerves and to broadly differentiate certain types of peripheral neuropathy.
These tests also help to determine whether the pathology is focal (either from compression or trauma) or generalised (length-dependent); and whether it is affecting the axon (conductive component of the nerve) or myelin sheath (insulating component of the nerve that allows for fast conduction) or in some cases both (a “mixed” neuropathy).
These different types of pathology can be revealed through the characteristics of the NCS and/or EMG results and play an important role in determining an accurate diagnosis.
This is because they provide a clear, objective, quantified measurement of nerve function – in this sense, they essentially “make the invisible visible”.
Consider a case study which recently presented to one of our clinics. A patient with a known history of diabetes had presented to their GP with symptoms of “stocking” paraesthesia. The treating GP could easily have assumed this was simply a complication of the patient’s known diabetes, but elected instead to confirm this suspicion by requesting lower-limb NCS.
Surprisingly, these studies revealed results consistent with a severe, demyelinating generalised peripheral neuropathy, with no evidence of the axonal dysfunction that is typically seen in diabetic neuropathy.
This, in turn, steered the investigations down a completely different avenue including screening for dysproteinaemias, malignancies and hereditary causes.
This case highlights the importance of objectively documenting the function of peripheral nerves, even in cases in which the diagnosis appears “obvious”.
Corbett Neurophysiology Services has been providing premium-quality, bulk-billed NCS and EMG studies (including related consultation with a Neurologist) for some thousands of GP and specialist referrers and many public hospitals for twenty-five years. We usually have short waiting periods for appointments and offer clinics in Brisbane, Ipswich and the Gold Coast. We provide immediate results to patients, and comprehensive reports are sent to referring practitioners within 24 hours.
For more information visit www.corbett.com.au or phone 07 5503 2499.